That is the one bad thing about that plate. I managed to get in with a socket on a universal joint but I made up a tube nut to secure the bolt in place so now all I need to do is slacken the nut to release the plate and the bolt/tube nut stay in place. Basically the tube nut was just an M8 stainless bolt cut to length, OD turned to about 7mm then drilled through and tapped M6 internally and then the head skimmed down to about 2mm thick. If you have a lathe or know someone who does it may be worth doing.
